Electric catfish are the Nile River's most wonderous fauna. The fish’s ability to generate high-voltage electric fields fascinated ancient Egyptians, who featured the fish prominently in their art and used them to treat chronic pain.

Advances in the human understanding of electricity helped eighteenth century scientists to explain the nature of an electric catfish’s shocks and to identify the specialized electric organs that produce them. More recent advances in genomics have helped elucidate the genetic basis and evolutionary history of those amazing organs. Still, despite our millennia of familiarity and centuries of modern scientific study, there’s plenty left to learn about the electric catfish. In particular, are the fish immune to their own shocks?

Georg Welzel and Stefan Schuster from the University of Bayreuth in Germany recently published a study aimed at that very question. They compared the responses of electric catfish and goldfish to different electrical stimuli, observing the movements of the fish after exposure to electrical discharges from both another electric catfish and electrofishing electrodes. While the goldfish were greatly affected by electric shocks from electric catfish and completely immobilized by the electrodes, the electric catfish appeared to be completely unfazed by any shocks. 

Although this study showed that electric catfish are immune to their own shocks, exactly how they achieve that immunity remains unclear. The fish did not physically respond, so their bodies may be insulated against or tolerant to electricity. Regardless of which mechanism they use, these catfish have yet to lose their mystery or magic.